Yes, making annotations and bookmarks would be helpful. I'm very much a tactile person so I've more or less made up my mind to get the keyboard version if I do eventually get a Kindle. The more I research about the different e-readers, the more I'm convinced that I want the Kindle, if only because more hacks are available!
I'm still ambivalent about the need for a lighted cover, glow light technology or a third party clip-on light. I hardly ever read with the lights off, and I'm not a fan of LED lights. Exactly how readable/unreadable is the Kindle when it comes to indoor reading? My room lights are not very supermarket bright nor dim, somewhere in between I think.